Tohatsu/Mecury/Mariner 25/30 2 strokes

Thread starter CorrosionNut
Start date Dec 8, 2010

C

CorrosionNut

Cadet

Dec 8, 2010

#1

Just a word of warning if you own or are buying a new Tohatsu, Mercury or Mariner 25 or 30 two stroke which are all in fact Tohatsu only the label is changed..
In my opinion they have a design defect that makes them prone to corrosion if you are using them in salt water. I have raised this issue with Tohatsu Japan and they disagree, so you can be the judge of the situation.

These engines all have a large aperture about the size of your fist under the carburettor in the bottom of the engine shell. This aperture is not at all obvious. This will allow salt spray and water to enter the engine bay. To make things worse the engine cover is also vented at the top so the spray can blow straight through around the engine. This may mean your engine gets coated with salt over the summer season and may sit corroding over the winter months unless you have a serious desalting routine as part of your corrosion prevention.

In Australia, New Zealand, and the Pacific Islands these engines are sold with no mention of this serious short coming to unsuspecting purchasers like myself. I don?t know if this is the same elsewhere but I suspect so.

This problem has been recognised by Tohatsu Japan since 1985. I have their dealer maintenance bulletin (sent to me this month) of that year that states this. The bulletin shows that the engine cover was redesigned to incorporate a baffled air intake for the carburettor in the tilt hand grip at the top rear of the engine. A new grommet was designed and is available as an option ????? to close of the air intake under the carburettor and it notes that this helps stop corrosion.

The part number is Grommet D, Lower Cowl Part # 346-76161-0

In my opinion for salt water operation

1. All new Tohatsu/Mercury/Mariner 30 and 25 two stroke engines need to be fitted with the Grommet D, Lower Cowl Part # 346-76161-0 before they are sold in the Australia, New Zealand and the Pacific or anywhere else.
2. All such motors already sold need to be fitted free of charge with Grommet D, Lower Cowl Part # 346-76161-0 at their next service. All customers need to be sent a letter to inform them of this.

Sea Rider

Supreme Mariner

Dec 9, 2010

#2

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

Anyway, it's a perfect crime to winterize any engine without any proper cleaning maintenance whatsoever on the engine bay. Should apply periodically a coat of W-40 or any rust inhibitor just in case. All engines brands does not have water proof bays. Water droplets and humidity will find it's way in no matter how well you seal or care for an engine.

Happy Boating

2

204Angler

Seaman

Dec 9, 2010

#3

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

So you are saying that Mercury has had engine corrosion problems since 1985? I have never had a problem with any Merc and haven't always treated them with "respect"

TOHATSU GURU

Admiral

Dec 9, 2010

#4

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

CorrosionNut said:
Just a word of warning if you own or are buying a new Tohatsu, Mercury or Mariner 25 or 30 two stroke which are all in fact Tohatsu only the label is changed..
In my opinion they have a design defect that makes them prone to corrosion if you are using them in salt water. I have raised this issue with Tohatsu Japan and they disagree, so you can be the judge of the situation.

These engines all have a large aperture about the size of your fist under the carburettor in the bottom of the engine shell. This aperture is not at all obvious. This will allow salt spray and water to enter the engine bay. To make things worse the engine cover is also vented at the top so the spray can blow straight through around the engine. This may mean your engine gets coated with salt over the summer season and may sit corroding over the winter months unless you have a serious desalting routine as part of your corrosion prevention.

In Australia, New Zealand, and the Pacific Islands these engines are sold with no mention of this serious short coming to unsuspecting purchasers like myself. I don?t know if this is the same elsewhere but I suspect so.

This problem has been recognised by Tohatsu Japan since 1985. I have their dealer maintenance bulletin (sent to me this month) of that year that states this. The bulletin shows that the engine cover was redesigned to incorporate a baffled air intake for the carburettor in the tilt hand grip at the top rear of the engine. A new grommet was designed and is available as an option ????? to close of the air intake under the carburettor and it notes that this helps stop corrosion.

The part number is Grommet D, Lower Cowl Part # 346-76161-0

In my opinion for salt water operation

1. All new Tohatsu/Mercury/Mariner 30 and 25 two stroke engines need to be fitted with the Grommet D, Lower Cowl Part # 346-76161-0 before they are sold in the Australia, New Zealand and the Pacific or anywhere else.
2. All such motors already sold need to be fitted free of charge with Grommet D, Lower Cowl Part # 346-76161-0 at their next service. All customers need to be sent a letter to inform them of this.

Your opinion is ridiculous and based on nothing. Corrosion is due to lack of operator maintenance...Nothing more and nothing less. All outboard owners manuals, regardless of brand, tell you to clean under the cover. Your post, your first one here oddly enough, is libelous and could easily be construed as product bashing. However, I think the moderators should let it stay as it clearly indicates how incredibly one dimensional people can be.

C

CorrosionNut

Cadet

Jul 29, 2011

#5

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

204Angler said:
So you are saying that Mercury has had engine corrosion problems since 1985? I have never had a problem with any Merc and haven't always treated them with "respect"

Up until about 2000 Mercury engines were manufactured by Mercury and they didn't have the problem problem. Since about 2000 Mercury have been selling re-badged Tohatsu 25 and thirty 2 strokes they have the problem. Probably only an issue if you operate in salt water.

C

CorrosionNut

Cadet

Jul 29, 2011

#6

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

TOHATSU GURU said:
Your opinion is ridiculous and based on nothing. Corrosion is due to lack of operator maintenance...Nothing more and nothing less. All outboard owners manuals, regardless of brand, tell you to clean under the cover. Your post, your first one here oddly enough, is libelous and could easily be construed as product bashing. However, I think the moderators should let it stay as it clearly indicates how incredibly one dimensional people can be.

My opinion is based on the corrosion that occurred over the first year of use despite being sprayed with w-40. The boat stays on a mooring when not at sea. I emailed Tohatsu Japan about the problem and they said the dealer who sold the engine to me should have fitted the grommet to seal the redundant air intake under the carburettor for my type of use. I probably use my boat a little more that you do, in that season we were away over sixty nights and travelled about 2000km. The less salt you have under the engine coner the better.

D

dimerz

Cadet

Jul 30, 2011

#7

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

CorrosionNut said:
My opinion is based on the corrosion that occurred over the first year of use despite being sprayed with w-40. The boat stays on a mooring when not at sea. I emailed Tohatsu Japan about the problem and they said the dealer who sold the engine to me should have fitted the grommet to seal the redundant air intake under the carburettor for my type of use. I probably use my boat a little more that you do, in that season we were away over sixty nights and travelled about 2000km. The less salt you have under the engine coner the better.

Just about every Surf Life Saving Club in Australia use this motor. If corrosion was a issue we wouldn't use them. They also end up upside down fairly regularly highlighted by this Facebook group. We ran one for around 9 years without any corrosion problems.

C

CorrosionNut

Cadet

Jul 30, 2011

#8

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

dimerz said:
Just about every Surf Life Saving Club in Australia use this motor. If corrosion was a issue we wouldn't use them. They also end up upside down fairly regularly highlighted by this Facebook group. We ran one for around 9 years without any corrosion problems.

I am well aware of the use of these motors by SLSNZ and SLSA. Both these organisation did extensive testing of these engines before adopting them as standard equipment and are well aware of the redundant air intake. They also have comprehensive desalting and anti corrosion standard procedures as a result of this knowledge and of course the type of use, even so the still have corrosion issued relating to the carburetor and choke. I know because I talked to the SLSNZ officer responsible for IRBs. Incidently IRB use in SLS was pioneered in NZ.

The general public are sold these engines without the knowledge that salt water and spray can enter the through the bottom air vent and with two air vents you will have a constant flow of water vapor rich air and fine spray through the engine bay a real problem for my type of use where the engine is on the boat in the water 24/7 on a mooring or at seas. Tohatsu manufacture a grommet specifically to close the redundant lower air intake and said in reply to my email to them about my corrosion issue that a grommet should have been fitted to my engine by the dealer.

My advice is if you own one of theses engines which you operate in salt water fit a grommet and minimise engine salt exposure. The choice is yours to make. Every one buying one of these motors should be told the facts and have that choice.

D

dimerz

Cadet

Jul 30, 2011

#9

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

CorrosionNut said:
They also have comprehensive desalting and anti corrosion standard procedures as a result of this knowledge and of course the type of use.

If by comprehenive you mean spray with a hose and and an occasional squirt of WD-40 then yeah I spose so.

C

CorrosionNut

Cadet

Jul 30, 2011

#10

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

dimerz said:
If by comprehenive you mean spray with a hose and and an occasional squirt of WD-40 then yeah I spose so.

Wash down, DW-40 and SaltAway after every use I was told.

C

CorrosionNut

Cadet

Jul 31, 2011

#11

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

TOHATSU GURU said:
Your opinion is ridiculous and based on nothing. Corrosion is due to lack of operator maintenance...Nothing more and nothing less. All outboard owners manuals, regardless of brand, tell you to clean under the cover. Your post, your first one here oddly enough, is libelous and could easily be construed as product bashing. However, I think the moderators should let it stay as it clearly indicates how incredibly one dimensional people can be.

You are only committing libel if you are spreading and untruth and Tohatsu Japan had no problem with my email to them.

They should have supplied the engine with the redundant air intake blocked since the 1985 design change which was obviously in response to corrosion problem.

As far as product bashing is concerned, my only objective has been to inform buyers and users of this design defect.

Apart from the corrosion issue the motor has performed extremely well.

Sea Rider

Supreme Mariner

Jul 31, 2011

#12

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

We sell the 30 model, haven't seen the grommet you mentioned placed in none of them factory delivered, still no corrosion problems, spry W-40 frequently, have sealed with silicone gasket maker every single hole under carb's engine bay, that way water intrusion is minimized.

Happy Boating

C

CorrosionNut

Cadet

Aug 1, 2011

#13

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

Sea Rider said:
We sell the 30 model, haven't seen the grommet you mentioned placed in none of them factory delivered, still no corrosion problems, spry W-40 frequently, have sealed with silicone gasket maker every single hole under carb's engine bay, that way water intrusion is minimized.

Happy Boating

The Tohatsu part number is 346-67161-0. There is a diagram showing it in the M25C3/M30A4 parts manual. This applies only to the two stroke model. This is an option and isn't factory supplied which I think it should be. The hole is almost big enough to put your fist through and is directly under the carb. It's quite difficult to see as opening to the outside as the engine pan is very close to the transom mount clamp bracket and it's all painted black. Far too big to block with silicone.
See Service Bulletin No. SB85001 dated January 7 1985 page four. Tohatsu Japan sent me a copy in reply to my email to them about the corrosion problem I was having.

The grommet sells for about $25

I've attached a photo with the redundant air intake temporarily blocked with closed cell foam

Sea Rider

Supreme Mariner

Aug 1, 2011

#14

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

Have rotated the pic for better undertandig, anyway, not knowing about this rubber grommet, nobody has complaint about corrosion, clients frequently spray W-40 on total engine pan, was reffering to the small holes on front pan, where you place nuts. That part is listed as an option on parts manual, if protects against water intrusion, agree, should be included factory standard.

Happy Boating

C

CorrosionNut

Cadet

Aug 1, 2011

#15

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

Sea Rider said:
Have rotated the pic for better undertandig, anyway, not knowing about this rubber grommet, nobody has complaint about corrosion, clients frequently spray W-40 on total engine pan, was reffering to the small holes on front pan, where you place nuts. That part is stated as an option on parts manual, if protects against water intrusion, should be included factory standard.

Happy Boating

Tohatsu Japan expect dealers to be advising customers as to whether a grommet should be fitted. They expect you to be familiar with Service Bulletin SB85001 despite the fact that it came out in January 1985. As my guy who sold me the motor said "Iwas only nine years old when that bulletin was issued!!!" For fresh water it isn't an issue really. For salt water it is an issue in my opinion. Unfortunately the service bulletin is to big to attach. Have attached picture of my boat which isn't probably your normal installation.

D

dimerz

Cadet

Aug 4, 2011

#16

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

CorrosionNut said:
Wash down, DW-40 and SaltAway after every use I was told.

I've never used or heard of SaltAway being used.

Sea Rider

Supreme Mariner

Aug 4, 2011

#17

Re: Tohatsu/Mecury/Mariner 25/30 2 strokes

dimerz said:
I've never used or heard of SaltAway being used.

Saltaway is a product that mixes with water generally used for flushing engine on after boating to remove salt formations inside engine's water passages, or rinsing sea water salt away from trailers, boats, trucks, etc not as a exterior corrosion inhibitor like W-40.

Happy Boating

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